1. Field of the Invention
The present invention relates to a slim type optical pick-up device for recording and/or reproducing information into and from an optical disk.
2. Description of the Background Art
In general, an optical pick-up device records and/or reproduces information by transmitting and receiving a light to and from the optical disk. According to an notebook computer or an portable disk player is more and more slim, the optical pick-up device for an notebook computer or an portable disk player is needed more compact
FIG. 1 is a schematic view showing the construction of an optical pick-up device in accordance with a conventional art.
As shown in FIG. 1, in the conventional optical pick-up device, a frame 20 is installed at a rear side of a yoke plate 10, and a printed circuit board (PCB) 30 is mounted at a rear side of the frame 20 and connected to an pick-up driving circuit through a flexible print circuit (FPC) 33.
An outer yoke 12 and an inner yoke 13 stand at a front side of the yoke plate 10, and permanent magnets 17 and 18 are fixed in a facing manner between the two yokes 12 and 13.
A holder 40 is positioned at a front side of the yoke plate 10, which is supported by four suspension wires 35 connected to the PCB 30.
The holder 40 includes an objective lens 41 for focussing light radiated from a light source on a recording layer of the optical disk, and a magnetic driving coils 45 for varying a position of the holder 40 horizontally and vertically according to the mutual interaction with the permanent magnets 17 and 18.
The frame 20 is provided with holes 21, through which the suspension wires 35 pass. The suspension wires 35 are made of a conductive material so that a signal outputted from the PCB 30 can be applied to the magnetic driving coils 45.
In the optical pick-up device, in a state that the holder 40 is supported by the suspension wires 35, as it moves vertically and horizontally according to a mutual interaction between the magnetic driving coils 45 and the permanent magnets 17 and 18, the position of the objective lens 41 can be varied, and accordingly, focussing and tracking operations are performed.
With reference to FIGS. 2 through 4, a coupling structure between the yoke plate 10, the frame 20 and the PCB 30 will now be described.
FIGS. 2 and 3 are a side view and a plan view showing the coupling structure of the yoke plate, the frame and the PCB, and FIG. 4 is a development view of the yoke plate.
With reference to FIG. 4, as for the yoke plate 10, an outer yoke 12 and an inner yoke 13 are formed bent upwardly at the front side of a bottom portion 11, side portions 14 are formed bent upwardly at both sides of the yoke plate 10, and a fixing portion 15 is formed bent upwardly at the rear side.
A fixing portion 15 includes a hole 15a at the central portion to engage a screw 31 therethrough.
With reference to FIGS. 2 and 3, in the yoke plate 10, the permanent magnets 17 and 18 are fixed in a manner of attaching to the outer yoke 12 and the inner yoke 13, and the frame 20 and the PCB 30 are threaded by the screw 31 at the rear side of the fixing portion 15.
However, the conventional optical pick-up device as described above has the following problem. That is, as shown in FIGS. 2 and 4, since the height and the width of the inner yoke 13 are formed shorter and smaller than those of the outer yoke 12, the inner yoke 13 has a relatively restricted coercive force of the permanent magnet 18, at which an operation characteristic of the optical pick-up device is degraded.
The reason why the inner yoke 13 is formed smaller than the outer yoke 12 is that, with reference to FIG. 4, the hole 15a is formed in the fixing portion 15 of the yoke plate 10, through which the PCB 30 and the frame 20 are threaded by the screw 31, and in this respect, in order to obtain a sufficient supporting force against the PCB 30 and the frame 20 as well as to provide the hole 15a at the fixing portion 15, there is a limitation to reduce the area of the fixing portion 15. Otherwise, if the optical pick-up device is desired to be designed compact under the condition that the fixing portion 15 is enlarged, the size of the inner yoke 13 is relatively reduced.
Consequently, in order for the fixing portion 15 to form the hole 15a for threading as well as obtain a sufficient supporting area, the inner yoke 13 is inevitably limited in its size.
If the fixing portion 15 is designed to have a sufficient supporting area while increasing the size of the inner yoke 13, the overall yoke plate 10 is enlarged, causing a problem that the optical pick-up device wouldn""t be designed compact.
The above-described conventional optical pick-up device has another problem. The PCB 30 and the frame 20 are fixed by being threaded by one screw 31 at the fixing portion 15 of the yoke plate 10, so that if the engaging force of the screw 31 is weakened or due to the typically flexible characteristic of the PCB 30, as shown in FIG. 5, when the holder 40 is moved vertically or horizontally, the PCB 30 and the frame 20 are simultaneously moved, causing an abnormal movement of an objective lens 41, resulting in failure of a normal focussing and tracking operation.
In other words, when the holder 40 is moved according to a mutual interaction between the magnetic driving coil 45 and the permanent magnets 17 and 18, if the PCB 30 connected to the suspension wires 35 are inclined vertically or horizontally, the central axis of the objective lens 41 would deviate from the center position as shown in FIG. 5. And at this time, a normal focussing and tracking operation do not made, so that the performance of the optical pick-up device is degraded.
Therefore, an object of the present invention is to provide an optical pick-up device which is capable of being designed more compactness while heightening a coercive force of a permanent magnet and capable of improving an operation characteristic and performance for an optical pick-up by fixing a PCB and a frame at a yoke plate without being shaken.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided an optical pick-up device including: a yoke plate having yokes formed at a front side where a magnetic body and a magnetic driving unit are positioned to drive an objective lens; a frame fixed to the yoke plate in such a manner that a portion of the rear side of the yoke plate is inserted thereinto; and a PCB with at least two portions fixed to the frame, for applying a drive signal to the magnetic driving unit.
In the optical pick-up device of the present invention, the yoke plate includes: an outer yoke bent in the orthogonal direction to a bottom portion at the front side; an inner yoke cut at the middle portion of the yoke plate and bent in the same direction of the outer yoke; and an insertion portion bent in the orthogonal direction to the bottom portion so as for the frame to be fixed thereto.
In the optical pick-up device of the present invention, the outer yoke and the inner yoke are formed having the same size, and the insertion portion is formed in a xe2x80x98Uxe2x80x99 shape.
In the optical pick-up device of the present invention, as for the inner yoke, its upper portion is cut at the inner portion of the insertion portion beyond the line where the insertion portion is bent from the bottom portion.
In the optical pick-up device of the present invention, the objective lens and the magnetic driving unit are installed at a holder, and the holder is supported by a plurality of suspension wires connected to the PCB.
In the optical pick-up device of the present invention, the frame includes holes through which the suspension wires pass, and the holes are formed with its upper portion opened so that the suspension wires can be easily inserted thereto.
In the optical pick-up device of the present invention, a thread hole is formed at both the PCB and the frame, and a screw is engaged at the thread holes of the PCB and the frame, and at the same time, at least one portions of the PCB and the frame are attached by an adhesive to be mutually fixed.
In the optical pick-up device of the present invention, the mutually fixed portions between the PCB and the frame are formed rectangular, and the rectangular four corner portions are attached by an adhesive.
In order to obtain the above objects, there is further provided an optical pick-up device including: a yoke plate having yokes formed at a front side where a magnetic body and a magnetic driving unit are positioned to drive an objective lens; and a frame fixed to the rear side of the yoke plate, wherein an insertion portion is formed at a rear side of the yoke plate and an insertion hole is formed at the frame so that the insertion portion is press-fit to the insertion hole, thereby fixing the frame to the yoke plate.
In the optical pick-up device of the present invention, the PCB is fixed to the frame by being attached at least three portions by using an adhesive without a screw.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.